Patent GB-965168-A (GB)
Title: An adjustable joint, especially for chairs, beds, cots, and the like
IPC: A01D34/66
Filed: 1962-12-29
Abstract: 965,168. Seats; bedsteads. W. BAHMULLER. Dec. 29, 1962, No. 48975/62. Heading A4J. [Also in Division E2] In an adjustable joint, for chairs and beds, having two arms, 6, 1 pivotable relative to each other, the arm 6 being provided with a locking part 7 having a locking range, while the arm 1 carries a locking member 2 which in its active position is operatively associated with the locking part 7 so as to produce the locking effect and which is also movable to an inactive position in which it is not in engagement with the locking part 7, the locking member 2 is acted upon by a control lever 10 which at a pivoting movement of the arm 6 in either direction is also pivoted about a certain angle and co-operates with the locking member 2 in such a manner that the locking member, which in one end position of the arms 6, 1 is moved to the inactive position, is maintained by the control lever 10 in the inactive position when the arm 6 carrying the locking part 7 is pivoted in the locking direction, and is moved by the control lever 10 to the active position when the pivoting direction of the arm 6 is changed. As shown in Fig. 1 the arm 6 is pivotably connected by means of a rivet 5 to a fixed arm 1. The locking member is a pawl 2 pivotable about a rivet 3 on the fixed arm 1. A leg 8 is also pivotable about the rivet 3 and may be locked in an operative position to a part 9 rigidly secured to the adjustable arm 6. The control lever 10 (Fig. 2) is pivotably connected to the rivet 5 in such frictional engagement with the side walls 7a, 7b of the locking part 7 that when the arm 6 is pivoted about the rivet 5 it also pivots the control lever 10. When the joint is used on a folding camp bed the leg 8 is moved to the operative position shown in Fig. 1. The arm 6 is then pivoted in the direction of the arrow II until the back rest has been moved to the desired angle. During this movement a projection 15 on the pawl 2 engages a detent 16 on the control lever 10 so that the arm 6 moves freely. When the desired angle is reached the arm 6 is pivoted slightly in the opposite direction whereupon a hooked shaped part 11 on the lever 10 acts on a detent 12 on the pawl 2 and turns the latter clockwise to disengage the projection 15 and detent 16. If the arm 6 is pivoted again in the direction of the arrow II, the detent 16 will engage the back of the projection 15 as shown in Fig. 3 and the pawl will be turned in a clockwise direction into engagement with the teeth of the locking part 7 on the arm 6. The joint is thus locked in adjusted position. If the back rest is thereafter to be adjusted to a steeper angle it need only be pivoted upwards for the desired distance from the position shown in Fig. 3. The hook 11 will press against the detent 12 of the pawl and urge it in the direction of the locking part 7. A tooth 13 on the pawl will snap from one tooth space on the ratchet member into another until the back rest has been adjusted to the desired angle. If the back rest is to be readjusted to a lower angle, pawl 2 must first be moved to its inactive position. This is achieved by pivoting the arm 6 clockwise to a vertical position until a locking surface 14 of the tooth 13 of the pawl runs up upon a higher cam portion 19 (Fig. 1) provided on the locking part 7. As shown in Fig. 4 the control lever 10 is used to move the pawl 2 into the inactive position, the hook part 11 engaging a projection 20 on the pawl 2. In a modification shown in Fig. 5 the part 7 has a cylindrical surface which may be knurled and the member 2 has an eccentric surface 210. In a further modification, Fig. 7 (not shown) the locking part 7 may be in the form of a clamping ring frictionally enclosing a journal disc rigidly secured to a fixed arm 1 by rivets. In the embodiment shown in Fig. 9 the locking part may consist of two conical surfaces 27 adapted to engage corresponding wedge shaped parts 28 of the locking member 2.